Field of the Invention
The invention relates to a measuring device having at least one sensor device, a processing device, a storage device, an interface and a control device, wherein the measuring device generates a measured value for a measured variable, wherein the sensor device generates a primary measured variable associated with the measured variable, wherein the processing device determines the measured value for the measured variable based on calculation data from the primary measured variable stored in the storage device and wherein the control device controls data traffic via the interface. Furthermore, the invention relates to a measuring arrangement having at least one measuring device for generating a measured value for a first measured variable and having at least one secondary measuring device for generating a measured value for a second measured variable.
Description of Related Art
Measuring devices are used in modern process technology to monitor or, respectively to regulate or control processes. In particular, in the case of critical applications, it is necessary, in respect to the reliability of individual measuring devices, that they are checked or that at least an adaptation to the aging processes takes place by means of a possibly necessary recalibration.
Such a test of the measuring device, or ideally, of all components of the device in respect to correct functionality is performed, in particular, regularly or in a fixed time pattern. The monitoring can also be performed by a mechanism present in the measuring device itself. In this manner, it is known in measuring devices, for example, to read back the issued current signal and compare it to a set point. Internal pulse frequencies or voltages are also monitored. In a broad sense, this belongs to the area of diagnostics, wherein, normally, the actual measuring process is not interrupted and the method proceeds automatically.
Furthermore, so-called proof tests are known that are usually triggered manually or with time control. For this, the measuring operation is normally interrupted for the duration of the tests or the measuring devices are even dismounted from their respective measuring sites. The dismounting allows, for example, a subsequent testing of the measuring device under the well-defined conditions of a laboratory or the examination of individual components, for which dismounting of the measuring device is necessary.
A great difference between a diagnosis of the functionality and a proof test is, thus, that the diagnosis takes place automatically, and normally, without interruption of the actual measuring operation, while the proof test takes place manually, or in particular, in the off-line mode of the measuring device.
Normally, measuring devices are not provided alone in a process, but form a measuring arrangement with other units, devices or apparatuses, which is established in an appropriate process environment. Such measuring arrangements can provide the advantage that individual measuring devices complement one another in the sense of redundancy or diversity.
A measuring device for measuring at least one measured variable or for generating a measured value thereby normally has at least one sensor device, a processing device, a storage device, an interface and a control device.
The measured variable is, for example, fill level, flow, mass flow, pressure, viscosity, pH value, temperature or conductivity. The sensor device generates a primary measured variable in conjunction with the measured variable, which is processed by the processing device. In particular, the processing device generates the measured value based on calculation data from the primary measured variable that is stored in the storage device.
Controlling the measurements is carried out by the control device. The control device also controls, in particular, the data traffic via the interface, i.e., issuing the measured value or retrieving and inputting further external data.
The measuring device is thereby described in respect to the functional distribution of the individual components. However, this does not have to take place in the specific implementation, rather it is possible that, for example, the processing device and the control device are included in one unit, wherein the storage device is optionally also directly installed.
In the broad sense, a measuring arrangement is understood to be a combination of at least two measuring devices. Thereby, this is a measuring device for generating a measured value for a first measured variable. This measuring device is, for example, the above-described measuring device, wherein the measured variable, which the measuring device is to measure, is the first measured variable here. Furthermore, at least one secondary measuring device is provided for generating a measured value for a second measured variable. The measuring device for the first measured variable could, thus, also be called a primary measuring device.